
#------------------------------------------------------------------------------
# $File: statistics,v 1.3 2022/03/24 15:48:58 christos Exp $
# statistics:  file(1) magic for statistics related software
#

# From Remy Rampin

# Stata is a statistical software tool that was created in 1985. While I
# don't personally use it, data files in its native (proprietary) format
# are common (.dta files).
# 
# Because they are so common, especially in statistical and social
# sciences, Stata files and SPSS files can be opened by a lot of modern
# software, for example Python's pandas package provides built-in
# support for them (read_stata() and read_spss()).
# 
# I noticed that the magic database includes an entry for SPSS files but
# not Stata files. Stata files for Stata 13 and newer (formats 117, 118,
# and 119) always begin with the string "<stata_dta><header>" as per
# https://www.stata.com/help.cgi?dta#definition
# 
# The format version number always follows, for example:
#    <stata_dta><header><release>117</release>
#    <stata_dta><header><release>118</release>
# 
# Therefore the following line would do the trick:
#    0       string  <stata_dta><header>     Stata Data File
# 
# (I'm sure the version number could be captured as well but I did not
# manage this without a regex)
# 
# Unfortunately the previous formats (created by Stata before 13, which
# was released 2013) are harder to recognize. Format 115 starts with the
# four bytes 0x73010100 or 0x73020100, format 114 with 0x72010100 or
# 0x72020100, format 113 with 0x71010101 or 0x71020101.
# 
# For additional reference, the Library of Congress website has an entry
# for the Stata Data File Format 118:
# https://www.loc.gov/preservation/digital/formats/fdd/fdd000471.shtml
# 
# Example of those files can be found on Zenodo:
# https://zenodo.org/search?page=1&size=20&q=&file_type=dta
0	string	\<stata_dta\>\<header\>\<release\>	Stata Data File
>&0	regex	[0-9]+					(Release %s)
